Agitator ball mills of this type are used for example for the fine-grinding or dispersion of solids in a liquid. For this purpose, agitator ball mills comprise a grinding chamber into which grinding bodies, for example in the form of grinding beads made of steel, glass or wear-resistant ceramic material are introduced up to a desired degree of filling. The degree of filling is determined among other things by the size of the grinding bodies or the consistency of the grinding material, with an as uniform as possible distribution of movement of the grinding bodies being sought. Arranged in the grinding chamber is an agitator which in the simplest case comprises a shaft having an agitator element arranged thereon which can be driven in a rotary manner in order to move the grinding bodies. For the grinding, a grinding material is introduced into the chamber which flows through the grinding chamber as often as required, depending on the desired degree of grinding.
Such agitator mills are already known from the prior art. EP 1 992 412 discloses an agitator ball mill, which comprises a vertically arranged container comprising a pot-shaped inner stator arranged therein. The agitator projects into this inner stator and comprises an annular-cylindrical rotor having tools extending in the radial direction up to close to the container wall. The grinding chamber is formed between the rotor and the container wall and is also embodied annular-cylindrical. Arranged at the lower end of the grinding chamber which is essentially closed off there is a deflection channel that leads to a narrow, annular gap-shaped discharge channel for the grinding material, said discharge channel being formed between the inner wall of the annular-cylindrical rotor and the inner stator. Centrally arranged at the upper end of this discharge channel is a screen for retaining the grinding bodies, which is however permeable for the grinding material once the latter has reached the required degree of grinding. Furthermore, return channels leading outwards in the radial direction are provided at the upper end of the discharge channel, said return channels serving to convey individual grinding bodies that have entered into the discharge channel back again into the grinding chamber. A likewise centrally arranged grinding material discharge line is arranged downstream of the screen in the direction of flow.
For a complete cleaning of the mill, in particular of the container, the rotor and the screen, as must be performed regularly when a switch is made from one grinding material to another, in the agitator grinding mill according to EP 1 992 412 the screen together with the grinding material discharge line is pulled out downwards after loosening of the corresponding screws. The container also must be unscrewed and disassembled, in order that the annular gap between the rotor and the container wall or the inner stator can be cleaned reliably and without residues remaining. Such absolutely residue-free cleaning is very particularly important for applications in the area of pharmaceuticals (but not only in this area) since the contamination of a product, for example by residues of the product previously ground with the agitator ball mill, must be avoided without fail. In this regard, the agitator ball mill described above is disadvantageous because it requires expensive dismantling and disassembly of various components of the mill, as is described above, in order to be able to perform a residue-free cleaning. After the cleaning, the reassembly then must be performed before the agitator ball mill is ready for use again and the next grinding material can be ground.